backoffice: add warning if total number of data fields is too large (#88452)

tests/admin_pages/test_block.py

@@ -485,7 +485,6 @@ def test_blocks_category(pub):
 def test_removed_block_in_form_fields_list(pub):
     create_superuser(pub)
 
-    BlockDef.wipe()
     FormDef.wipe()
     formdef = FormDef()
     formdef.name = 'form title'

wcs/formdef.py

@@ -581,10 +581,13 @@ class FormDef(StorableObject):
         for field in self.fields or []:
             if not field.key == 'block':
                 continue
-            count += (
-                len([x for x in field.block.fields or [] if not x.is_no_data_field])
-                * field.default_items_count
-            )
+            try:
+                count += (
+                    len([x for x in field.block.fields or [] if not x.is_no_data_field])
+                    * field.default_items_count
+                )
+            except KeyError:
+                continue
         return count
 
     def iter_fields(self, include_block_fields=False, with_backoffice_fields=True, with_no_data_fields=True):